This invention relates to tools for use in the removal of tubular inserts from fittings and, in particular, to tools for use in the removal of tubular inserts that have been previously bonded to a fitting by soldering or the like.
In many occupations, workmen are required to remove a tubular insert from a fitting in which at least a portion of the insert is snugly received. Frequently, the insert to be removed has been previously bonded to the fitting by the use of solder or a similar heat-sensitive bonding agent. Plumbers, for example, are frequently required to reroute various sections of the plumbing tubing which typically necessitates the physical separation of joints and fittings which have been previously soldered together to form a leak-proof, solid bond. In such cases, one piece of tubing is usually cut near the joint to be broken, heat is applied to melt or otherwise defeat the bond, and the inner tubular insert is extracted. This extraction process typically requires that the fitting or tube from which the insert is extracted be left in an undamaged condition.
A common extraction technique employed in the past proceeds by grasping a portion of the severed end of the tubing insert with the jaws of a pair of ordinary pliers and manually applying a pulling force in a direction away from the joint to be disengaged while applying heat to the joint. This technique suffers from several disadvantages. First, it is exceedingly difficult to maintain the purchase required to forcibly extract the insert over the length of time required to soften the bond with the applied heat. While this difficulty may be overcome by simply applying heat for an extensive period of time and then grasping the insert with the plier jaws and pulling, this solution is normally unsatisfactory since the application of excessive heat to the fitting to be retained permanently weakens the fitting. Moreover, where the severed tubing insert comprises a relatively soft material, e.g. copper or Teflon, sufficient purchase is virtually impossible to obtain since the plier jaws tend to chew or gouge the material. Further, if excessive gripping pressure is applied across the diameter of the severed tubing insert, the insert deforms both externally and internally of the fitting, which increases the resistance to separation and also tends to deform the fitting, rendering the latter useless. In addition, since ordinary pliers are fabricated from a relatively effective heat conductor, e.g. steel, the heat required to loosen the bond is quickly conducted via the fitting and severed tubing to the handle portion of the pliers, and the temperature of the handle portion is consequently raised to such a degree that the operator must release his grip or risk severe burns. While this difficulty may be alleviated by wearing a heat-insulative glove, or by wrapping the handle portion with an effective heat insulator, this solution impairs the manual dexterity of the operator.
Efforts have been made to design extraction tools to overcome the above-noted disadvantages encountered with the use of pliers, and for use in applications in which the insert cannot be gripped by the plier jaws, e.g. in the removal of bearing inserts. Representative examples of such tools are found in U.S. Pat. Nos. 736,991; 2,671,263; 3,052,973; 3,055,093; and 3,181,396. Such tools typically employ a generally cylindrical, radially expandable gripping member which is adapted to be introduced into the interior of the insert to be removed and a cooperating expander member for expanding the gripping member into surface engagement with the insert. In some known tools, the gripping member has a smooth outer surface; in others, a rough surface is provided, which may comprise a plurality of longitudinally spaced, circumferentially extending ridges, a helical screw thread or the like.
While such known tools have been found to be generally more effective than ordinary pliers, several difficulties have been encountered with the use of such devices. For example, the gripping elements of some devices expand radially in an uneven fashion so that only a limited portion of the available gripping surface of the gripping element is forced into surface engagement with the insert. As a result, the insert and fitting are typically deformed or scored when the insert is pulled from the fitting. This problem is amplified if the outer surface of each gripping element is provided with ridges or teeth since the ridges or teeth can tear through the tubing insert and damage the fitting, particularly if the insert and fitting comprise a relatively soft material. Moreover, some devices are constructed so that the gripping elements are allowed to rotate as they are expanded into surface contact with the interior of the insert. If the gripping element is provided with teeth, this rotational action can facilitate tearing through the insert by the teeth with resultant damage to the fitting. Additionally, many such devices are of all-metal construction so that the application of heat to loosen the bond between the insert and the fitting can cause the handle of the device to be raised to a temperature that can cause an operator to experience severe discomfort or a burn. Finally, a number of such extraction tools are of special construction making them inappropriate for portable, field use. Efforts to design an extraction tool devoid of the above limitations have not met with success to date.